What is the difference between the obstetric term and the calendar. Calculate embryonic gestation
The pregnancy calculator allows you to calculate the exact due date and find out what week of pregnancy you are currently in, as well as the expected due date. To calculate, select the date of the first day of your last period at the top of the calculator and click on the "Calculate" button. The calculator will then automatically display your current week of pregnancy and your expected due date.
For each week of pregnancy, two precise dates are displayed: start day and end day. The interval between them is exactly 7 days. You can scroll through the weeks of pregnancy using the arrows. A complete list of weeks 1 through 40 is at the very bottom of the calculator. By clicking on them, you can also turn the slider to the desired week. The trimester of pregnancy, to which each week belongs, is indicated by Roman numerals at the bottom (near the slider) and in the upper right corner of the cells (in the full list of weeks). Also, trimesters are indicated in pink, orange and blue, respectively. In general, the very concept of pregnancy trimesters is rather arbitrary and their boundaries are not clearly defined. We took as a basis the most common classification, in which the second trimester starts at the 14th week and ends at the 28th. Only your obstetrician-gynecologist after an ultrasound examination can calculate the trimesters more accurately.
In the pictures you can see a rough illustration of the development of the baby inside the womb for each week. To the left of the images is a summary of fetal growth for that week. More complete and detailed information you can find by following the link "More", which is located under each description.
Method for calculating the duration of pregnancy
The calculator calculates the so-called "obstetric" gestational age. It differs from the actual period by about two weeks. This calculation method is used in gynecology, because it is very difficult to calculate the exact day of conception. Therefore, the calculation is based on the first day of the last menstruation, the date of which, as a rule, every woman remembers. 280 days or 40 weeks are added to this day. Thus, during the first two weeks of your obstetric period, you are not yet pregnant. ovulation has not yet occurred (based on an average menstrual cycle of 28 days). This method is not completely accurate as some women ovulate late or early. But, in general, for most expectant mothers, such a calculation turns out to be quite accurate.
In any case, we draw your attention to the fact that the pregnancy calculator allows you to calculate the period according to the most general formula, which does not take into account individual characteristics your body. It cannot be used for self-diagnosis or any other medical purposes, since the results of its calculations are for informational purposes only. All accurate calculations and any other manipulations should be done only by your doctor.
Pregnancy calendars
Calculate your pregnancy calendar by week. Each week of your pregnancy from 1 to 40 weeks with details.
Pregnancy is an amazing and exciting period in a woman's life. In just 40 weeks, a whole organism is formed from one cell, capable of living in the surrounding conditions. A person never develops at such a fast pace again as in the prenatal period. Every day the appearance of the fetus changes, new organs and new abilities appear. The appearance and well-being of a woman are also rapidly changing - even last month her “interesting position” was not noticed by anyone, and today a nice round tummy has already appeared. During gestation, you need to do a lot - you will have to go through more than one medical examination, pass several tests, revise your menu and sleep patterns, change habits and update your wardrobe. It is better to prepare for all changes in life in advance and especially so that you are aware of all the upcoming surprises, we have prepared a detailed weekly pregnancy calendar.
Where does the confusion come from in two weeks?
Doctors in antenatal clinics traditionally count the gestational age from the first day of the last menstrual period, despite the fact that conception occurs, according to such calculations, only in the third week of pregnancy. Our interactive calendar is built in the same way - this is the so-called obstetric pregnancy calendar. There is another, much less commonly used, method of calculating the timing of pregnancy, when the day of conception is taken as the starting point. The resulting calendar, it would be correct to call the calendar of the development of the fetus. Sometimes this method is displayed in the conclusions of obstetric ultrasound, where it is possible, with an accuracy of one day, to establish the life expectancy of the fetus, especially in the first trimester. Typically, the fetal development calendar is about 2 weeks behind the obstetric pregnancy calendar.
It is most logical to schedule the pregnancy by week - so you will have a better idea of how your baby is growing and what processes pregnancy causes in your own body. By studying the pregnancy calendar by week, you will find timely advice on how to choose clothes for pregnant women, how to avoid toxicosis, how to eat right during pregnancy. Accordingly, the size of the fetus and its new skills are given each week - you will be surprised at how much it already has, when even the tummy is not yet visible to others!
In order to automatically calculate the pregnancy calendar, you can use the calculator on the website. It is enough to indicate the date of the first day of your last period, and you will receive a calendar of your own pregnancy by week. Perhaps this should be interesting for a pregnant woman - every week to learn about how her baby's life is going, but you should not take the given terms literally. Keep in mind that the duration of pregnancy, as well as the rate of development of the fetus, is always individual and may differ slightly from the data provided by the interactive pregnancy calendar. The following pattern is characteristic - the longer the duration of the menstrual cycle, the longer the pregnancy lasts.
Questions to the article
Gram? Weight before pregnancy 80 kg, now 82.700. And seven weeks ago it was ...
They said. And now I wonder))) which one? ...
The estimated date was 7/4/17. But I still haven't given birth and nothing ...
Cough, no fever. I am treated with chamomile, milk and honey, my nose is nothing ...
4 times a day. And at 10 pm I can eat. This is fine? I have 10 ...
Obstetric week, I did it in Moscow, they appointed a divigel and ...
The fetus. This is fine. Sometimes there are imperceptible tremors. I have...
I did 3 tests, all 3 showed a weak second strip, the next ...
Reading 100102 .... this is normal that I am very worried, tell me ...
Date of conception - 03/15/2017 HCG 04/06/2017 - 6145.2 mIU / ml. Moreover, in less than 48 ...
Free, the result of 2.0 ng / ml is pregnancy ??? ...
Which is 6 weeks old, but shows how much more. And the ultrasound showed 4 weeks. Maybe...
1 day delay the day before the start of menstruation watched the test showed ...
Ml. Ultrasound on January 11, 2017 did not show anything. Please tell me this ...
The doctors and the ultrasound scan were fine, but for the last three days I started to get sick ...
Received Belarus. On cancellation, menstruation came in the first cycle (33 days ...
Could it affect the baby? and can my gynecologist prescribe ...
11/30/16 on hCG - the result is 1062.2. What does it mean? ...
Placental abruption 20mm by 4mm. Zistka said nothing, it will grow. And ...
2x five days)? 14 DPP - 1290 Me / L, 19 DPP - 6149 Me / L? The Uzi has just ...
Pain began in the pubic bone area when walking and when ...
The second one is already bright. And in the evening, smearing spotting a little ...
September, in October they are not) What week do I have? How to calculate? ...
A week. Last monthly 12.09.16 ctcl 30 days. The gynecologist says ...
The last menstruation was 04/27/4/05. May 5th was protected sex ...
I read you in the article that it could be a fetus with down syndrome ...
Syphilis recently surrendered by her husband: anti-Treponema pallidum Ig M negative, ...
The condom broke, can there be a chance of pregnancy? ...
Rev. KP.) (Reference values 1,1 are positive. What does this mean? ...
Be monthly. Did tests 28, 30 and so on. All negative. By 8 ...
For weeks they found a cat at home and he is constantly at home on the street ...
Sometimes a little 3-4 times a day is it normal pregnancy 16 weeks? ...
Menstruation was noted not expressed pain in the lower abdomen, now ...
My throat ached, followed by a stuffy nose, not big snot, isn't it dangerous ...
1.00-5.00 and immature granulocytes 0.3% reference. interval 0.0-0.2. What is it ...
Vozmojno chto ya beremenna? I esli da, to kakoy srok? Pojalusta otvette esli mojno? ...
Menstruation 07/19/20015. Thanks!...
Placental abruption. If I understand correctly, the embryo receives less ...
The previous children also had a tone and the doctor constantly scares me ...
(there 16 years are missing) PERSONAL PREGNANCY CALENDAR FOR ...
Weeks! A small runny nose, sore throat and weakness! isn't it like this ...
The lower abdomen is like during PMS, there is no bloody discharge, is it dangerous ...
11/28/15 hCG showed 11564, which corresponds to 4 weeks of pregnancy, ...
At 6-7 weeks there was a threat of miscarriage, with a second pregnancy it can ...
Years, the cycle was about 34-35 days, but not exactly. pregnancy on ...
The test showed that she was pregnant. but I don't remember the date of the last ...
Consider that, according to calculations, I should have gained at least 5kg ...
Regular. The delay is now 7 days. Negative tests On the 16th day of the cycle ...
Accounting for pregnancy with a weight of 76.4 kg (period of 5-6 weeks). Then I sharply ...
Menya.vozmojno beremennost v etom mesyace? I chto mojno zdelat zaranee chtob eto ne sluchilos? ...
The onset of menstruation was 09/02/15, in fact, conception occurred from 3 to 5 ...
They arrived with a delay of 2-3 days, the end in my opinion is 7.05 or 8.05. Sexual intercourse at ...
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Many women, finding themselves in a position, do not know how to establish the gestational age. Medicine offers two approaches, called "obstetric" and "fetal". But which one would be more accurate? Let's figure out how pregnancy is calculated by week. For some mothers, even after childbirth, this information remains a mystery.
When does pregnancy occur?
To find out the "age" of the unborn baby, you need to know at what point pregnancy occurs. In the middle of the menstrual cycle, the egg leaves the follicle and travels through the fallopian tubes. After meeting with the sperm, chromosomes merge and conceive. Then the ovum descends into the uterine muscle and attaches to the walls of the uterus. From this moment, the pregnancy is considered complete.
Why do you need to know the timing?
The calculation of pregnancy by week is not done due to the curiosity of the mother (although this factor is also important). It determines the date of future birth.
Another important indicator is the development of the embryo. A correctly set period helps the doctor determine whether the child is growing in the womb in accordance with the norm, helps to maintain pregnancy in the early stages. In the case of a delay or anomaly of development, a frozen pregnancy, it is the knowledge of the moment of conception that helps to establish the pathology.
If it is difficult to find out the approximate time of the onset of pregnancy, look at the development of the fetus. By its size and other indicators, the age of the embryo is determined thanks to ultrasound.
What is Obstetric Pregnancy?
Finding out the exact time of conception is always difficult. In this regard, the date when the last menstruation began is important for doctors. From her, the obstetric period is counted and it turns out how long the pregnancy will last.
Traditionally, a woman's menstrual cycle is 28 days. The most likely time for conception is 14 days after the onset of menstruation, when ovulation occurs. The real (embryonic) period will differ from the obstetric one by 2 weeks. For example, if the obstetric period is 5 weeks (from the beginning of menstruation), then the embryo will be in the third week of development (from the moment of conception).
However, the individual characteristics of a woman's body can adjust the standards established by medicine. Statistics say that only 40-50% of women conceive 2 weeks after the start of the last menstrual period. 20% of women require much less time for fertilization.
The main difference between the obstetric term of pregnancy and the real one is that it is guided by the date of menstruation, and the embryonic one - by the date of fertilization. Due to the fact that each organism lives according to its own "laws", the difference between the periods can reach 3 weeks.
Why calculate it?
Since the obstetric period of pregnancy and the real one are so different, the question arises: why bother calculating the obstetric period, if you can find out the real one? But this is the main difficulty. There are many obstacles in determining the real time of conception of a baby.
- Women and midwives had to calculate the timing of pregnancy for a long time, when there was still no ultrasound and knowledge about ovulation. The only indicator was the absence of bleeding.
- The timing of the menstrual cycle is different for all women. It is almost impossible to accurately calculate the day of ovulation. We have to focus on the day of the onset of menstruation.
- Not always a woman can remember exactly the day of sexual intercourse. At the same time, fertilization could occur 2-3 days later.
- Modern medicine also uses other methods to accurately determine the time of conception: ultrasound, finding out the size of the fetus and uterus, the timing of the first movement of the baby.
How to calculate the deadline correctly?
Anyone can calculate the obstetric gestational age without a doctor's advice future mom... If you know the date of the last menstrual period and the duration of the menstrual cycle, it is enough to calculate the time from it to the moment you learned about the pregnancy. The length of the cycle is worth considering, as with a longer cycle, conception may have occurred later than usual.
If the exact date of your period is not known, you can resort to using HCG analysis. Thanks to him, you can find out the approximate age of the embryo.
To find out the embryonic date, the exact date of sexual intercourse or conception must be known. If a woman does not have such information, modern tests equipped with electronic sensors can help her. They determine the timing of pregnancy with a small error.
The obstetric term helps to find out the date of future birth. There are several ways to do this:
- subtract 3 months from the last day of menstruation and add 1 week;
- add 9 months and 1 week or 280 days to the last day of menstruation.
Ultrasound examination
Ultrasound will help to find out obstetric or real terms. It is routinely carried out during pregnancy at 10-14 weeks, however, the doctor can examine the ovum as early as 4 weeks.
A more accurate date is set when the embryo reaches 6-7 weeks (according to the obstetric time), along the length of the embryo blast. Late attempts to find out the age of the embryo will have errors, since a genetic predisposition is increasingly manifested in the physical development of the child. For example, in some of the children, development may be ahead of the norm, and then, based on the measurements, the doctor will set an earlier date.
In the future, the pregnant woman will undergo an ultrasound scan at 20-24 and 30-34 weeks. At this time, doctors look at the correspondence of the development of the fetus to its age, based on the previously established gestational age, and determine whether the child is growing normally.
Modern experts use generally accepted norms regarding the bearing of a woman's fetus. Pregnancy without complications lasts an average of 280 days. Usually, the very beginning of the term means the first day of the last menstrual bleeding. This counting system is called obstetric timing. In modern gynecology, according to such data, the time of prenatal leave is calculated, the size of the fetus is estimated by ultrasound, and the estimated date of birth is calculated.
What is Obstetric Pregnancy Week?
The specialist, in order to determine the time of delivery by the obstetric method, counts exactly three months from the initial day of the last menstrual bleeding back, then adds 7 days to the result. It should be borne in mind that the resulting date of birth is not an exact day, but a certain range that can recede 10-12 days forward or backward from the most likely day of the natural birth of the fetus. Each pregnancy follows a unique scenario, so the time for carrying a baby varies. It has been noticed that specialists mainly operate with the concept of obstetric term, because almost every unexpectedly pregnant woman can name the date of the last menstruation, since it is customary to record these data in the calendar, but few people will be able to accurately indicate the day when conception occurred.
A feature of the obstetric period of pregnancy is that it contains the full cycle of the birth of a new life, that is, the time from the beginning of the life of the egg, and until the appearance of a fully developed and ready for life in the external world of the child. There is nothing complicated in how obstetric weeks of pregnancy are counted. The week itself, as usual, is 7 days. The difference was found to be hidden in the number of months. We know that the gestation period is 9 calendar months, which is equal to 10 obstetric months, which is an average of 40 weeks - if you count from the date of your last period, and 38 weeks - if you start from the date of conception.
Obstetric gestational age: exceeds the embryonic term by 14-15 daysDetermining the duration of pregnancy
What is embryonic gestation?
It is known that in medical practice, the embryonic gestation period is also calculated, which begins with the fact of conception and, as a rule, coincides with the time of ovulation. A woman's menstrual cycle, lasting from the first day of her period until the first day of her next period, is usually between 28 and 30 days. During the first part of the cycle, the follicle matures inside the ovary, by the 14-15th day, the ovulation process is observed, implying the release of the formed egg from the follicle. It has been scientifically proven that after ovulation for about 2 more days, the egg retains the ability to fully further develop through fertilization. It is also taken into account that the sperm produced by a man are viable and prone to fertilization for about 4 days. It turns out that only 6 days have the highest probability of conception. Based on the foregoing, a feature of the obstetric term can be distinguished: it certainly exceeds the embryonic one. The difference between these concepts is 14-15 days.
Calculation of gestational age according to ultrasound
It is theoretically possible to calculate the gestational age based on the size of the uterus and the nature of fetal movements. These criteria cannot be considered accurate, because these are strictly individual data with a significant scatter. In fact, the fetus begins to move at 7-8 weeks of life, but the mother may feel tremors at 18-20 weeks. Every woman needs to have an idea of ovulation and fetal timing, monitor her own menstrual cycle, and at least in general terms know how obstetric weeks of pregnancy are counted. Having accurate data will facilitate medical follow-up and increase the chances of a normal delivery of a healthy baby.
Today, many unenlightened people mistakenly believe that pregnancy can be determined by performing an ultrasound scan. In reality, this is not the case. The main task of ultrasound is to assess the state of the embryo. Experts are trying to find out with what gestational age the real size of the fetus is comparable, based on the estimated period, calculated directly from conception or the beginning of the last menstrual bleeding. Ultrasound is prescribed at least 3 times to assess the dynamics of development and growth of the fetus in accordance with the gestational age.
For example, it was previously found out that the period is 32 weeks, and the ultrasound examination showed such dimensions of the fetus, which are inherent only in a 29-week-old embryo. In this case, doctors will not adjust the period according to the size, but conclude that there is a developmental delay of 3 weeks, and this implies a detailed examination and determination of the cause of the deviations.
In many cases, the pregnancy is proceeding normally, and an ultrasound scan reveals the correspondence between the size of the fetus's body and the established period. This fact gives rise to a false statement that an ultrasound examination is a way to determine the duration of pregnancy.
Based on the above information, we can conclude that it is really important for expectant mothers to know how obstetric weeks of pregnancy are counted. Experts emphasize that the correct gestational age in weeks can be established by examining the totality of data, which includes the following indicators: fetal growth dynamics, the onset of the last menstrual bleeding, the results of several ultrasound examinations and the date of conception.